Temporally- And Spatially-Resolved Single Photon Counting Using Compressive Sensing For Debug Of Integrated Circuits, Lidar And Other Applications

Abstract

A method for photon counting including the steps of collecting light emitted or reflected / scattered from an object; imaging the object onto a spatial light modulator, applying a series of pseudo-random modulation patterns to the SLM according to standard compressive-sensing theory, collecting the modulated light onto a photon-counting detector, recording the number of photons received for each pattern (by photon counting) and optionally the time of arrival of the received photons, and recovering the spatial distribution of the received photons by the algorithms of compressive sensing (CS).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61 / 306,817 entitled “Temporally- And Spatially-Resolved Single Photon Counting Using Compressive Sensing For Use In Integrated Circuit Debug And Failure Analysis” and filed by the present inventors on Feb. 22, 2010.[0002]The aforementioned provisional patent application is hereby incorporated by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0003]None.BACKGROUND OF THE INVENTION[0004]1. Field of the Invention[0005]The present invention relates to systems and methods for integrated circuit debug and failure analysis, and more specifically, to systems and methods for temporally- and spatially-resolved single photon counting using compressive sensing.[0006]2. Brief Description of the Related Art[0007]A theory known as Compressive Sensing (CS) has emerged that offers hope for directly acquiri...

AI Technical Summary

Benefits of technology

[0017]The present invention will improve the performance of instruments that acquire spatially- and temporally-resolved photon-counting data. The performance gain comes from the compressive sensing techniques described in the Background section above, which allow faster acquisition times and / or higher signal to noise ratios compared to the state of the art (BS or RS). The signal to noise ratio at each pixel will be approximately the same at every pixel as in the original single-element detector. (The average photon counts will be reduced by a factor of 2 at every pixel due to the 50% duty cycle of the spatial light modulator.) The technique relies on an SLM to provide spatial resolution and a single-element PC detector, along with inversion of the CS data. Using CS it is possible to acquire a number M, which is far fewer then N, measurements which provides a speed up or SNR improvement. A typical ratio of M / N for still images is about 10% for high quality reconstruction, representing a 10× improvement over RS. The useful M / N ratio should decrease further in the case where the data is also temporally-resolved, as the data cube (2 spatial dimensions and 1 temporal dimension) is much larger than in the 2D case, and sparsity should yield an even greater advantage for CS over BS. The present invention may employ the CS reconstruction techniques disclosed in Baraniuk et al., U.S. Pat. No. 7,271,747. Some specific applications include: failure analysis and debug of integrated circuits and LIDAR (Laser Detection and Ranging).

Problems solved by technology

Unfortunately, this requires a combinatorial search, which is prohibitively complex.

Most photon counting devices, such as standard PMTS and APDs, are incapable of providing spatial as well as temporal resolution.

Such spatially-resolved photon counters are very expensive and typically offer reasonable but not excellent temporal resolution (100-150 ps).

Thus there is a large SNR penalty of order N incurred by raster-scanning.

An array detector would not incur this penalty, but as described above such detectors are often not available, or are too costly, or do not have sufficient performance for the application.

An additional problem with RS is the slow speed of acquisition—a 1 MPix image could easily take several seconds to acquire due to the limited speed of the scanning mirrors.

One disadvantage of the BS technique is that it is often limited by the speed of the SLM—e.g. a digital micromirror device can only produce on the order of 50,000 patterns per second, meaning that to acquire 1 Mpix image would require about 20 seconds, which can be too long for many applications (including video processing.

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